It is certainly bad in terms of longevity. Google Wave was temporary; email is forever. Of course, the downside of federation is complexity. Matrix.org is a g

It is certainly bad in terms of longevity. Google Wave was temporary; email is forever. Of course, the downside of federation is complexity. Matrix.org is a great choice for an open federated messaging protocol, but the challenges of operating in that kind of ecosystem have certainly stunted their ability to add features and polish when compared to a closed system such as Zulip.